Muscle activity with the mandibular lip bumper

This prospective study was designed to measure muscle activity with Tip bum per treatment. Surface electromyography was used to measure upper and lower lip activity with and without the appliance in place. Measurements were ta ken on a sample of 25 adolescent patients (age range, 10 to 17 years) befor e and after 12 months of lip bumper treatment. Recordings included a closed lip rest position, swallowing of water, and speech of the words "church," "phone," and "pop." Insertion of the lip bumper at the pretreatment recordi ng resulted in significantly increased activity of the upper and lower lips at rest (P < .001) and while swallowing (P < .05), whereas the response fo r speech was variable. Pretreatment and posttreatment muscle activity measu rements of the lower lip were compared to determine whether 12 months of tr eatment with the appliance resulted in muscle adaptation. The initial incre ase of muscle activity with insertion of the appliance for the closed lip r est position and for swallowing was not followed by a decrease during the t reatment period. There were significant differences in muscle activity when comparing the "new" equilibrium introduced by the lip bumper to the "old" pretreatment equilibrium without the appliance. Although it was shown that the insertion of the appliance had a significant influence on muscle activi ty of the lips, the results of this study did not indicate adaptation of th e lower lip to the appliance over the treatment period.